Fitness dynamics within a poplar hybrid zone: II. Impact of exotic sex on native poplars in an urban jungle

Abstract

Trees bearing novel or exotic gene components are poised to contribute to the bioeconomy for a variety of purposes such as bioenergy production, phytoremediation, and carbon sequestration within the forestry sector, but sustainable release of trees with novel traits in large-scale plantations requires the quantification of risks posed to native tree populations. Over the last century, exotic hybrid poplars produced through artificial crosses were planted throughout eastern Canada as ornamentals or windbreaks and these exotics provide a proxy by which to examine the fitness of exotic poplar traits within the natural environment to assess risk of exotic gene escape, establishment, and spread into native gene pools. We assessed postzygotic fitness traits of native and exotic poplars within a naturally regenerated stand in eastern Canada (Quebec City, QC). Pure natives (P. balsamifera and P. deltoides spp. deltoides), native hybrids (P. deltoides × P. balsamifera), and exotic hybrids (trees bearing Populus nigra and P. maximowiczii genetic components) were screened for reproductive biomass, yield, seed germination, and fungal disease susceptibility. Exotic hybrids expressed fitness traits intermediate to pure species and were not significantly different from native hybrids. They formed fully viable seed and backcrossed predominantly with P. balsamifera. These data show that exotic hybrids were not unfit and were capable of establishing and competing within the native stand. Future research will seek to examine the impact of exotic gene regions on associated biotic communities to fully quantify the risk exotic poplars pose to native poplar forests.

An Empirical Assessment of Transgene Flow from a Bt Transgenic Poplar Plantation

“…deltoides . They also found that the majority of gene flow (more than 98%) was intraspecific [23, 24]. DiFazio et al reported that the mean pollination distance for P .…”

Genome and Transcriptome Sequencing of Populus × sibirica Identified Sex-Associated Allele-Specific Expression of the CLC Gene

“…The genus Populus is presented by dioecious species and, due to extensive genetic studies ( Tuskan et al, 2006 ; Jansson and Douglas, 2007 ; Jansson et al, 2010 ), is a promising object for research of differences between sexes. Poplars are wind-pollinated trees, and different species are easily crossed, resulting in the emergence of natural interspecific hybrids and a high level of genetic diversity ( Rae et al, 2007 ; Roe et al, 2014 ; Jiang et al, 2016 ).…”

Genetics polymorphism of poplars from Moscow region based on high-throughput sequencing of ITS

“…Poplars are dioecious wind-pollinated plants that leads to high intraspecies diversity (Rae et al, 2007). It is known that various species of poplar are easily crossed forming natural interspecific hybrids (Roe et al, 2014;Jiang et al, 2016) that poses difficulties in identifying their taxonomic status. Genome of P. trichocarpa was sequenced in 2006 being the first genome of a tree (Tuskan et al, 2006).…”